This invention relates to an image formation apparatus which makes use of an optical system to scan a document.
There have been image formation apparatus equipped with an automatic document feeder and capable of scanning by moving an optical system both a bulky original, such as a book, and a sheet-like document placed on a document table. When many sheet-like documents are successively scanned by such an apparatus, the documents are fed one sheet at a time from a document supplying section disposed at one end in the upper part. Since the optical system usually must start from its home position to scan each document, it must return to this home position after each scan and this results in a waste of time.
For this reason, a new type of apparatus has been considered which includes a rotary cylinder around which a document transported from the document supplying section is wrapped and rotated such that the document can be scanned by a stationary optical system. Such a cylinder, however, must have a large enough circumference in order to accommodate documents of all sizes. A bulky original such as a book, however, cannot be handled by such an apparatus depending entirely on a cylinder to feed original documents.
U.S. Pat. No. 3,833,296 issued Sept. 3, 1974 to Vola, et al. discloses a scanning system which can be operated in two modes. When a copy is made from a bulky original such as a book, it is placed on a horizontal glass plate and is scanned by a moving optical system. A smaller sheet-like original, on the other hand, can be fed through an exposure device and exposed by a stationary optical system such that copies can be made quickly. With this device, however, selection between the two modes of operation cannot be made automatically and it was up to the user to decide for each original document which of the modes to be used.